Antioxidants for producing low-emission pur systems

ABSTRACT

A compound of the formula (I) 
     
       
         
         
             
             
         
       
     
     in which
     R is CH 2 —CH(R I ), CH(R II )—CH(R II ), CH 2 —C(R II ) 2 , C(R II ) 2 —C(R II ) 2 ,   

     
       
         
         
             
             
         
       
         
         
           
             CH 2 —CH—CH 2 —R IV , C 6 H 6 —CH—CH 2 , C 6 H 6 —C(CH 3 )—CH 2 , where 
           
         
         R I  is C 2  to C 24  alkyl radical or alkene radical, 
         R II  is C 2  to C 24  alkyl radical or alkene radical, 
         R III  is C 3  to C 6  alkyl radical, which is arranged linearly, and 
         R IV  is OH, Cl, OCH 3 , OCH 2 —CH 3 , O—CH 2 —CH═CH 2 , O—CH═CH 2  molecule residue of epoxidized fats or oils, 
         R 1  and R 2  independently of one another are C 1 -C 8  alkyl, cyclopentyl or cyclohexyl, especially tert-butyl, 
         R 3  is an n-valent radical of C 1 -C 30 -alkyl, 
         R 4  is hydrogen, an n-valent radical of C 1 -C 30  alkyl, which is optionally interrupted by one or more groups —NR 5 — or (where n=1-12) is an n-valent radical of C 5 -C 12  cycloalkyl, 
         R 5  independently at each occurrence is hydrogen or methyl or —C q H 2q .

RELATED APPLICATION DATA

The present application hereby claims priority to European ApplicationNo. EP 15 158 424.0 filed Mar. 10, 2015, which is incorporated herein byreference in its entirety.

FIELD

The present invention is situated within the field of antioxidants andalso within the field of plastics, more particularly of polyurethanes.It concerns, in particular, new antioxidants, antioxidant mixtures, andpolyurethane systems, especially polyurethane foams.

BACKGROUND

Antioxidants are compounds of various chemical structures and areintended to inhibit or prevent unwanted alterations, caused by oxygenexposure and other oxidative processes, in the substances underprotection.

They are required in plastics, for example, for protection from aging,since synthetic polymers are subject fundamentally to oxidation byoxygen, and impurities often present in small amounts may promote theoxidation process. This oxidation can lead to detrimental changes to themechanical properties of the polymer in question, and hence of thecomponent in which the polymer is used. This may result ultimately in anunwanted deterioration in function. In order to prevent or at leastinhibit such oxidation processes, therefore, antioxidants are used,examples being sterically hindered phenols.

This situation may also apply to the production of polyurethane systems,such as polyurethane coatings, polyurethane adhesives, polyurethanesealants, polyurethane elastomers or, in particular, polyurethanefoams/foam materials, for example.

Polyurethane systems, such as polyurethane foams in particular, are usedacross a wide variety of sectors, by virtue of their outstandingmechanical and physical properties. One particularly important marketfor a wide variety of types of PU foams (=i.e. polyurethane foams), suchas conventional flexible foams based on ether and ester polyol,cold-cure foams (frequently referred to also as HR foams), rigid foams,integral foams and microcellular foams, and also foams with propertiessituated between these classifications, such as semi-rigid systems, forexample, is that of the automotive and furniture industries. Forinstance, rigid foams are used as roof liner, ester foams as interiordoor trim and also for die-cut sun visors, cold-cure and flexible foamsare used for seat systems and mattresses.

There has been no lack of attempts to date to provide antioxidants whichare effective in particular with a view to the stabilization of polymersthat are susceptible towards oxidative, thermal or light-induceddegradation.

For example, hydroxyphenylcarboxylic esters can be used as antioxidants.There are numerous known compounds from the class ofhydroxyphenylcarboxylic esters. They can be prepared, for example, bytransesterification using suitable catalysts. Transesterificationprocesses of this kind are described in, for example, U.S. Pat. No.4,716,244, U.S. Pat. No. 5,481,023, U.S. Pat. No. 5,563,291,EP-A-1292560. EP-A-608089 describes esters of the above-statedstructural type that comprise polyethylene glycol groups. They too canbe prepared by transesterification, in which case the known stronglybasic catalysts are recommended, such as alkali metals and also alkalimetal amides, alkoxides, hydroxides and (bi)carbonates.

These and other known antioxidants are useful, but do not in everyrespect satisfy the exacting requirements asked of an aging inhibitorwhen the stabilization concerned is that of synthetic polymers,especially with regard to lifetime, water absorption, sensitivity tohydrolysis, process stabilization, color properties, volatility,migration characteristics, compatibility and improvement in protectionwith respect to light.

Consequently there still exists an ongoing need for possibilities forthe stabilization of synthetic polymers that are susceptible tooxidative, thermal and/or light-induced degradation.

SUMMARY

The specific problem addressed by the present invention against thisbackground was that of providing antioxidants which are suitable for thestabilization of synthetic polymers, especially with a view to theprovision of corresponding polyurethanes, preferably of polyurethanefoams.

Entirely unexpectedly it has now been found that a specific group ofcompounds of the type of the hydroxyphenylcarboxylic esters do justiceto this objective.

DETAILED DESCRIPTION

A subject of the present invention is a compound of the formula (I)

in which

-   R is CH₂—CH(R^(I)), CH(R^(II))—CH(R^(I)), CH₂—C(R^(II))₂,    C(R^(II))₂—C(R^(II))₂,

-   -   CH₂—CH—CH₂—R^(IV), C₆H₆—CH—CH₂, or C₆H₆—C(CH₃)—CH₂, where

-   R^(I) is C₂ to C₂₄ alkyl radical or alkene radical, which may be    linear or branched,

-   R^(II) is C₂ to C₂₄ alkyl radical or alkene radical, which may be    linear or branched,

-   R^(III) is C₃ to C₆ alkyl radical, which is arranged linearly, and

-   R^(IV) is OH, Cl, OCH₃, OCH₂—CH₃, O—CH₂—CH═CH₂, O—CH═CH₂, molecule    residue of singly or multiply epoxidized fats or oils as mono-, di-,    and triglycerides, or molecule residue of singly or multiply    epoxidized fatty acids or their C₁-C₂₄ alkyl esters,

-   R₁ and R₂ independently of one another are straight-chain or    branched C₁-C₈ alkyl, cyclopentyl or cyclohexyl, especially    tert-butyl,

-   q is 1, 2 or 3, preferably 2 or 3, especially 2,

-   n is an integer from 1 to 30, preferably an integer from 1 to 10,    advantageously 1, 2, 3, 4, 5 or 6, e.g. 1, 2, 3 or 4, especially 1,

-   R₃ is an n-valent radical of linear or branched C₁-C₃₀ alkyl,    preferably C₁-C₁₀ alkyl, C₂-C₃₀ alkylene, interrupted in each case    optionally by one or more oxygen atoms, or (where n=1-12) is an    n-valent radical of C₅-C₁₂ cycloalkyl, or a radical    R₄—[NR₅—C_(q)H_(2q)—]_(p),

-   R₄ is hydrogen, an n-valent radical of linear or branched C₁-C₃₀    alkyl, which is optionally interrupted by one or more groups —NR₅—    or (where n=1-12) is an n-valent radical of C₅-C₁₂ cycloalkyl,

-   R₅ independently at each occurrence is hydrogen or methyl or    —C_(q)H_(2q)—, preferably hydrogen, and

-   p corresponds to the number of [NR₅—C_(q)H_(2q)—] groups that    produces n radicals —C_(q)H_(2q)— per molecule,

-   k is an integer between 0 and 50, preferably between 10 and 30,

-   m is an integer between 0 and 50, e.g. 1-40, and

-   o is an integer between 0 and 50, preferably between 0 and 30,    especially 0,

-   where (k+m+o)>10.

The problem addressed by the present invention is solved by thissubject. It permits very effective stabilization of synthetic polymersagainst oxidative, thermal or light-induced degradation. This subjecthas proved to be particularly valuable and efficacious particularly inthe context of the provision of polyurethane systems, preferablypolyurethane foams, especially free-rise flexible polyurethane(slabstock) foams. The invention enables overall a substantialimprovement to be achieved in the sustained retention of the processingand performance features of polyurethane systems, especially PU foams.

If in the formula (I) k, m, o>0 or k, m>0 and at the same time o=0, thesequence of the monomer units ethylene oxide, propylene oxide and(R-oxide) in the individual polymer chains 1 to n is arbitrary, and k, mand o represent average values. Moreover, the individual units (EO),(PO) and (RO) can be bonded to one another either in the form of blocks,in strict alternation or in the form of gradients. In the form ofgradients means that in the individual chain there is a gradient in thedistribution of the (BO), (PO) and (RO) units along the chains.

Hydroxyphenylcarboxylic esters are sterically hindered phenols. Frommechanistics studies it is known that the functional group within thehydroxyphenylcarboxylic esters that counteracts the oxidativedegradation of polymers is the sterically hindered phenol unit.

All the more surprising is the fact that the mass fraction of phenolunits in the compounds of the formula (I) of the invention is smallerthan in existing compounds of the hydroxyphenylcarboxylic ester type andthat in spite of this an antioxidant effect (especially with regard tothe stabilization of synthetic polymers, such as preferably polyurethanesystems) is achieved that in fact exceeds the effect of knownhydroxyphenylcarboxylic esters. The real expectation would have beenthat a greater amount of the compounds of the formula (I) of theinvention would have been necessary in order to be able to achieve anantioxidative effect even only comparable to that of the knownhydroxyphenylcarboxylic esters. The opposite, however, can be observed.

A further wholly unexpected advantage of the compounds of the formula(I) of the invention is, moreover, that the use of the compounds of theinvention permits the provision of polyurethane systems, moreparticularly PU foams, which exhibit unexpectedly good emissionscharacteristics. The performance features of polyurethane systems, moreparticularly PU foams, are in fact improved accordingly.

Exemplary compounds of the formula (I) are the compounds Ia and Ib shownbelow.

The inventive use of the aforementioned compounds Ia and Ib correspondsto one preferred embodiment of the invention.

A further subject of this invention is a synthetic polymer, preferablypolyurethane system, more particularly PU foam, comprising at least onecompound of the formula (I).

Such polymers, especially polyurethane systems, are particularlyinsensitive to aging and particularly oxidation-resistant, and, moreparticularly, such foams exhibit unexpectedly good emissionscharacteristics. The influencing of the emissions characteristics ofsynthetic polymers, especially polyurethane (foam)s, is of greatsignificance.

Thus, for example, in the production and the subsequent use ofpolyurethane systems, such as foams in particular, the release ofemissions and fogging are problem factors. Fogging is understood as theemission of compounds which may subsequently condense, such as in avehicle interior, for example, on the windscreen, to form a usually hazycovering, for example.

Many consumers are therefore somewhat critical of polyurethane systemsand in some cases even have health concerns, despite the objective lackof any justification for health concerns, as demonstrated by results ofnoxious substance measurements. From both the consumer side and theindustry side, therefore, there is an ongoing desire for polyurethanesystems of this kind with the smallest possible release of emissions.

As part of this invention it has now been found that the compounds ofthe formula (I) of the invention permit the provision of polyurethanesystems, especially PU foam, with minimal release of emissions andminimal fogging, as compared with polyurethane systems in whichconventional antioxidants have been used.

A proven test method for assessing emissions that is established in themarket is, for example, the DaimlerChrysler testing instructions of VDA278: “Thermodesorptionsanalyse organischer Emissionen zurCharakterisierung nichtmetallischer KFZ-Werkstoffe” [Thermodesorptionanalysis of organic emissions for characterizing non-metallic vehiclematerial] of October 2011. The figure for the emissions of volatilecompounds is referred to below as VOC (VOCs=Volatile Organic Compounds).The value for the emissions of condensable compounds, corresponding tofogging, is referred to below as fog value. Appropriate methods for thedetermination of VOC and fogging are described with precision in theexamples section.

The use of the compounds of the formula (I) of the invention makes itpossible, advantageously, to produce polyurethane systems, especially PUfoams, which have very low values for volatile organic (VOC) andcondensable (fogging) compounds. It has been possible to achieve valuesof <100 ppm for VOC and of <250 ppm for fogging. The values for VOC andfogging may be determined in particular by means of thermodesorptionanalysis. Using the compounds of the formula (I) of the invention makesit possible, furthermore, advantageously, to produce polyurethanesystems, especially PU foams, which are particularly low in odor. Usingthe compounds of the formula (I) of the invention makes it possible,additionally, advantageously, to produce polyurethane systems,especially PU foams, which are particularly aging-resistant. Anotheradvantage of using the compounds of the formula (I) is that they can beutilized without complication in existing production operations and onexisting production lines.

The compounds of the formula (I) of the invention can be prepared by anysuitable process which is common knowledge within the field of thepreparation of compounds of this type, including various esterificationprocesses. Three examples of such processes are elucidated exemplarilyin the reaction schemes below, and are identified respectively asprocess A, process B and process C.

1) Process A

2) Process B

3) Process C

In the reaction schemes above, R, R₁, R₂, R₃ k, n, q, m and o have thedefinition given above for formula (I), R^(V) is a straight-chain orbranched-chain alkyl group having 1 to 4 carbon atoms, such as a methyl,ethyl, propyl, isopropyl, butyl or isobutyl group, for example,preferably a methyl group, and X is a halogen atom such as a chlorine orbromine atom.

The starting materials of the formula (V) are adducts of alkylene oxideswith various alcohols, and may be described as alkylene glycol alkylmonoethers or as O-alkylated alkylene glycols. It should be borne inmind that in the case of polyalkylene oxide adducts, the productsavailable commercially are often mixtures of two or more individualcompounds having different numbers of ethylene oxide, propylene oxideand/or R-oxide units. If a mixture of this kind is used as startingmaterial, the end product of the formula (I) consists of a correspondingmixture. It is therefore implicit that in the case of such mixtures, theindices k, m and o may denote an average number of ethylene oxide,propylene oxide and R-oxide units, respectively, and so they may befractional numbers for the overall mixture.

Process A encompasses a transesterification between the alkylene glycolmonoether of the formula (V) and the substituted phenolpropionic esterof the formula (IVa). This reaction can be carried out as desired in thepresence or absence of a solvent and in the presence of atransesterification catalyst.

If a solvent is used in this reaction, examples of suitable inertsolvents include ethers such as diisopropyl ether, dioxane andtetrahydrofuran, halogenated hydrocarbons such as carbon tetrachlorideand dichloroethane, linear or cyclic aliphatic hydrocarbons such ashexane, heptane, octane, isooctane, cyclohexane, methylcyclohexane,ethylcyclohexane and kerosine, and aromatic hydrocarbons such asbenzene, toluene and xylene. Aromatic hydrocarbons are preferred.

Examples of suitable transesterification catalysts include alkali metalssuch as lithium, sodium and potassium, alkali metal hydrides such aslithium hydride, alkali metal amides such as lithium amide, sodium amideand lithium N,N-diisopropylamide, alkali metal alkoxides such as sodiummethoxide, sodium ethoxide and potassium tert-butoxide, alkali metalhydroxides such as lithium hydroxide, sodium hydroxide and potassiumhydroxide, alkali metal carbonates such as lithium carbonate, sodiumcarbonate and potassium carbonate, alkali metal bicarbonates such aslithium bicarbonate, sodium bicarbonate and potassium bicarbonate,carboxylic salts of alkali metals and alkaline earth metals (for exampleacetates or formates) such as lithium acetate, sodium acetate, potassiumacetate or magnesium acetate and lithium formate, sodium formate orpotassium formate, aluminum alkoxides and phenoxides, titanium(IV)alkoxides such as titanium(IV) tetraisopropoxide and titanium(IV)tetrabutoxide, metal oxides such as tin oxide, metal-organic tin(IV)compounds such as dibutyltin oxide, or organic acids such asbenzenesulphonic acid, p-toluenesulphonic acid,trifluoromethanesulphonic acid and methanesulphonic acid, and mineralacids such as hydrochloric acid and sulphuric acid, preference beinggiven to mineral acids and sulphonic acids, especially sulphuric acid asmineral acid and p-toluenesulphonic acid as sulphonic acid. The alkalimetal alkoxides are preferred.

Reaction temperature and reaction time may vary depending on thestarting materials, the catalyst and the solvent (where used). Thetemperature, however, is generally 50 to 200° C., more preferably 80 to140° C., while the reaction time is commonly 2 to 24 hours, morepreferably 4 to 12 hours.

After the ending of the transesterification reaction, the desiredproduct of the formula (I) may be isolated by conventional techniques.For example, in the case of a basic reaction regime, the reactionmixture is washed and neutralized with a dilute mineral acid (e.g.dilute hydrochloric acid or sulphuric acid), after which insolubleconstituents are removed (by filtration, for example) and the resultingliquid is dried over a dehydrating agent (e.g. anhydrous magnesiumsulphate) and the solvent is evaporated. If desired, the productobtained may be purified, for example by distillation under reducedpressure or by column chromatography.

Process B encompasses the esterification of the alkylene glycolmonoether of the formula (V) with the substituted phenol propionic acidof the formula (IVb). This reaction is preferably carried out in aninert solvent and in the presence of an acid catalyst.

Examples of suitable inert solvents which can be used in this reactioninclude ethers such as diisopropyl ether, dioxane and tetrahydrofuran,halogenated hydrocarbons such as methylene chloride, carbontetrachloride and dichloroethane, aliphatic hydrocarbons such as hexane,heptane, octane, ethylcyclohexane and kerosine, and aromatichydrocarbons such as benzene, toluene and xylene. Aromatic hydrocarbonsare preferred.

The acid catalysts which can be used in this reaction include, forexample, sulphonic acids such as benzenesulphonic acid,p-toluenesulphonic acid, trifluoromethanesulphonic acid andmethanesulphonic acid, and mineral acids such as hydrochloric acid andsulphuric acid, preference being given to mineral acids and sulphonicacids, especially sulphuric acid as mineral acid and p-toluenesulphonicacid as sulphonic acid.

Reaction temperature and reaction time may vary depending on thestarting materials, the solvent and the catalyst, although thetemperature is generally 60 to 200° C., more preferably 100 to 150° C.,and the reaction time is generally 3 to 24 hours, more preferably 4 to12 hours.

After the ending of the esterification reaction, the desired product ofthe formula (I) may be isolated by conventional techniques. For example,the reaction mixture is washed and neutralized with an aqueous alkalimetal solution (e.g. aqueous sodium bicarbonate), after which insolubleconstituents are removed (by filtration, for example) and the liquidobtained is dried over a dehydrating agent (e.g. anhydrous magnesiumsulphate) and the solvent is evaporated, giving the product of theformula (I). If desired, the product may be purified, for example bydistillation under reduced pressure or by column chromatography.

Process C encompasses the esterification of the alkylene glycolmonoether of the formula (V) with the substituted phenylpropionyl halideof the formula (IVc). This reaction is carried out preferably in aninert solvent and in the presence of a hydrogen halide scavenger.

Examples of solvents suitable in this reaction include those alreadylisted for the reaction of process A.

Examples of suitable hydrogen halide scavengers include alkali metalhydroxides such as lithium hydroxide, sodium hydroxide and potassiumhydroxide, alkali metal carbonates such as lithium carbonate, sodiumcarbonate and potassium carbonate, alkali metal bicarbonates such aslithium bicarbonate, sodium bicarbonate and potassium bicarbonate,aliphatic tertiary amines such as triethylamine, trioctylamine,N-methylmorpholine and N,N-dimethylpiperazine, and pyridines such aspyridine and N,N-dimethylaminopyridine. Triethylamine and the pyridinesare preferred.

Reaction temperature and reaction time may vary depending on thestarting materials, the solvent and hydrogen halide scavenger that areused. However, the reaction temperature is commonly 0 to 120° C., morepreferably 10 to 60° C., while the reaction time is commonly 1 hour to12 hours, more preferably 4 to 8 hours.

After the ending of the reaction, the desired product of the formula (I)may be isolated by conventional techniques. For example, the reactionmixture is washed with a dilute mineral acid (e.g. dilute hydrochloricacid or sulphuric acid), after which insoluble constituents are removed(by filtration, for example) and the liquid obtained is dried over adehydrating agent (e.g. anhydrous magnesium sulphate) and the solvent isevaporated, giving the desired product. If desired, the product can bepurified, for example by distillation under reduced pressure or bycolumn chromatography.

The compounds of the formula (I) of the invention also allow theprovision of antioxidant mixtures. An antioxidant mixture in the senseof this invention comprises at least one further antioxidant as well asthe compound of the formula (I). In addition, if desired, there may alsobe further ingredients, such as solvents etc., for example. Thesesolvents are preferably selected from water, alcohols, especiallypolyether monools or polyols, preferably consisting of H-functionalstarter substances, onto which alkylene oxides (epoxides) having 2-24carbon atoms, preferably ethylene oxide and/or propylene oxide, havebeen added by alkoxylation, and which have a molecular weight ofpreferably 200-8000 g/mol, more preferably of 300-5000 g/mol, verypreferably of 500-1000 g/mol, and a PO content of preferably 10-100 wt%, more preferably of 50-100 wt %, and also polyester monools or polyolshaving a molecular weight preferably in the range from 200 to 4500g/mol, glycols, alkoxylates, carbonates, ethers, esters, branched orlinear aliphatic or aromatic hydrocarbons and/or oils of syntheticand/or natural origin.

The “further antioxidant” may be any known natural or syntheticantioxidant, more particularly those which are commonly used inconnection with preventing the oxidative degradation of plastics, PUsystems and/or adhesives.

Surprisingly, however, in the context of this invention, it has beenfound that specifically certain benzofuranone derivatives of the formula(II) cited below provide very particularly strong support for theefficacy of the compounds of the formula (I), allowing the term“synergistic interaction” to be used.

Compounds of the benzofuran-2-one type that are preferred accordingly inthe sense of this invention are compounds of the formula (II).

in which

-   a is an integer between 0 and 7, preferably 0-3, e.g. 1 or 2,-   R₆ and R₇ independently of one another are H or C₁-C₈ alkyl, e.g.    tert-butyl,

-   R₈ is H or an aromatic radical where-   R₉ and R₁₀ independently of one another are H or C₁-C₆ alkyl, with    not both being a C₁-C₆ alkyl,-   R₁₁ and R₁₂ independently of one another are H or C₁-C₆ alkyl, with    not both being a C₁-C₆ alkyl,-   R₁₃ is H or OH, especially OH.

Benzofuran-2-one stabilizers of the formula (II) are known in theliterature as such. Reference may be made here in particular to EP2500341.

More particularly it is possible in the sense of this invention, ascompound of the benzofuran-2-one type, to use the compound (IIa),

-   4-tert-butyl-2-(5-tert-butyl-2-oxo-2,    3-dihydro-1-benzofuran-3-yl)phenyl    3,5-di-tert-butyl-4-hydroxybenzoate (IIa).

The use of this compound of the formula (IIa) has shown particularlyadvantageous results in respect of the desired effects.

According to one preferred embodiment of the invention, an antioxidantmixture of the invention comprises compound(s) of the formula (I) in anamount of 75 to 99 wt %, preferably 80 to 98 wt %, more particularly 90to 95 wt %, and compound(s) of the formula (II) in an amount of 1 to 25wt %, preferably 2 to 20 wt %, more particularly 5 to 10 wt %, wt %being based on the total weight of the compounds of the formulae (I) and(II) used.

It has additionally been found that antioxidant mixtures of theinvention which comprise compound(s) of both formulae (I) and (II),particularly in combination with a phosphite (ester of phosphorousacid), are particularly advantageous. Phosphites which can be used withpreference accordingly are those having the general formula (III)

in whichR₁₄, R₁₅ and R₁₆ independently of one another are an aromatic oraliphatic, linear or branched radical of C₁-C₃₀-alkyl orC₂-C₃₀-alkylene, interrupted in each case optionally by one or moreoxygen atoms.

Particularly preferred examples of such phosphites are the commerciallyavailable compounds (IIIa), (IIIb) and (IIIc).

A compound of the phosphite type which can be used in particular in thesense of this invention is the compound (IIIa),tris(2,4-di-tert-butylphenyl) phosphite (IIIa).

The use of this compound of the formula (IIIa) has shown especiallyadvantageous results in respect of the desired effects.

According to one especially preferred embodiment of the invention, anantioxidant mixture of the invention comprises compound(s) of theformula (I) in an amount of 75 to 99 wt %, preferably 80 to 98 wt %,more particularly 90 to 95 wt %, and compound(s) of the formula (II) inan amount of 1 to 25 wt %, preferably 2 to 20 wt %, more particularly 5to 10 wt %, and compounds of the formula (III) in an amount of 0.1 to 20wt %, preferably 0.2 to 15 wt %, more particularly 0.5 to 10 wt %, wt %being based on the total weight of the compounds of the formulae (I),(II) and (III) used.

A further subject of this invention against the outlined background is aprocess for producing polyurethane systems, especially PU foam, byreaction of at least one polyol component with at least one isocyanatecomponent in the presence of one or more catalysts which catalyze theisocyanate-polyol and/or isocyanate-water reactions and/or theisocyanate trimerization, the reaction being carried out in the presenceof one or more compounds of the formula (I) or in the presence of anantioxidant mixture, as described above.

The PU system, more particularly the PU foam, is preferably produced byfoaming a mixture comprising at least one urethane catalyst and/orisocyanurate catalyst, at least one blowing agent and/or water, at leastone isocyanate component and a polyol component in the presence of oneor more compounds of the formula (I) or in the presence of anantioxidant mixture, as described above.

In addition to the stated components, the mixture may have otherconstituents, such as, for example, optionally (further) blowing agents,optionally prepolymers, optionally flame retardants and optionallyfurther additives (different from those identified in the additivecomposition of the invention), such as fillers, emulsifiers based on thereaction of hydroxy-functional compounds with isocyanates, foamstabilizers, such as Si-containing and non-Si-containing stabilizers,especially Si-containing and non-Si-containing organic stabilizers andsurfactants, viscosity reducers, dyes, UV stabilizers or antistats, forexample. It will be readily understood that the skilled person selectsthe substances necessary for producing the individual types of flexiblepolyurethane foam, i.e. hot-cure, cold-cure or ester foams of flexiblepolyurethane type, examples of such substances being isocyanate, polyol,prepolymer, etc., as appropriate for obtaining the particular desiredtype of flexible polyurethane foam.

A number of property rights describing suitable components and processesfor producing the different types of flexible polyurethane foam, i.e.hot-cure, cold-cure and also ester flexible polyurethane foams, areindicated hereinbelow and are fully incorporated herein by reference: EP0152878 A1, EP 0 409 035 A2, DE 102005050473 A1, DE 19629161 A1, DE3508292 A1, DE 4444898 A1, EP 1061095 A1, EP 0532939 B1, EP 0867464 B1,EP 1683831 A1 and DE 102007046860 A1.

Further details of usable starting materials, catalysts and auxiliariesand additives can be found, for example, in Kunststoff-Handbuch[Plastics Handbook], volume 7, Polyurethane [Polyurethanes],Carl-Hanser-Verlag Munich, 1st edition 1966, 2nd edition 1983 and 3rdedition 1993.

The compounds, components and additives which follow are mentionedmerely by way of example and can be replaced by other substances knownto those skilled in the art.

Surfactants employable in the production of flexible polyurethane foamsare selectable, for example, from the group comprising nonionicsurfactants and/or amphoteric surfactants.

Surfactants used may, in accordance with the invention, for example,also be polymeric emulsifiers such as polyalkyl polyoxyalkylpolyacrylates, polyvinylpyrrolidones or polyvinyl acetates. It islikewise possible to use, as surfactants/emulsifiers, prepolymers whichare obtained by reaction of small amounts of isocyanates with polyols(called oligourethanes), and which are preferably present dissolved inpolyols.

Foam stabilizers used may preferably be those which are known from theprior art and which are typically also employed for polyurethane foamstabilization. These may be both Si-containing and non-Si-containing,especially Si-containing and non-Si-containing organic stabilizers andsurfactants. The Si-containing stabilizers are further distinguished bywhether the polyoxyalkylene block is bonded to the polysiloxane block bya hydrolytically stable C—Si bond (as, for example, in EP 2 182 020) orby the less hydrolytically stable C—O—Si bond. TheSiC-polysiloxane-polyoxyalkylene block copolymers usable forpolyurethane foam stabilization can be prepared, for example, by noblemetal-catalyzed hydrosilylation of unsaturated polyoxyalkylenes withSiH-functional siloxanes, called hydrosiloxanes, as described, forexample, in EP 1 520 870. The hydrosilylation can be conducted batchwiseor continuously, as described, for example, in DE 198 59 759 C1.

A host of further specifications, such as EP 0493836 A1, U.S. Pat. No.5,565,194 or EP 1350804, for example, each disclosepolysiloxane-polyoxyalkylene block copolymers of specific compositionfor complying with specific profiles of requirements for foamstabilizers in diverse polyurethane foam formulations.

Biocides used may be commercial products such as chlorophene,benzisothiazolinone, hexahydro-1,3,5-tris(hydroxyethyl-s-triazine),chloromethylisothiazolinone, methylisothiazolinone or1,6-dihydroxy-2,5-dioxohexane, which are known by the trade names BIT10, Nipacide BCP, Acticide MBS, Nipacide BK, Nipacide CI, Nipacide FC.

Suitable flame retardants for the purposes of this invention are anysubstances considered suitable therefore in the prior art. Examples ofpreferred flame retardants are liquid organophosphorus compounds such ashalogen-free organophosphates, e.g. triethyl phosphate (TEP),halogenated phosphates, e.g. tris(1-chloro-2-propyl) phosphate (TCPP),tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tris(2-chloroethyl)phosphate (TCEP), and organic phosphonates, e.g. dimethylmethanephosphonate (DMMP), dimethyl propanephosphonate (DMPP), or solidssuch as ammonium polyphosphate (APP) and red phosphorus. Suitable flameretardants further include halogenated compounds, for examplehalogenated polyols, and also solids such as expandable graphite andmelamine. All of these flame retardants and combinations thereof may beutilized advantageously in the sense of this invention, and include allcommercially available flame retardants from the companies Great LakesSolutions (Chemtura) (e.g.: DP-54™, Firemaster® BZ-54 HP, Firemaster®Firemaster® 550, Firemaster® 552, Firemaster® 600, Firemaster® 602,Reofos® 50, Reofos® 65, Reofos® 95, Kronitex® CDP), ICL IndustrialProducts (e.g.: FR-513, FR-1210, FR-1410, Fyrol™ FR-2, Fyrol™ 38, Fyrol™HF-5, Fyrol™ A300 TB, Fyrol™ PCF, Fyrol™ PNX, Fyrol™ PNX-LE), Clariant(e.g.: Exolit® OP 550 or Exolit® OP 560).

In many cases, all of the components apart from the polyols andisocyanates are mixed prior to foaming, to give what is called anactivator solution. This solution then preferably comprises, among otheringredients, the additive composition which can be used in accordancewith the invention, i.e. compounds of the formula (I) or antioxidantmixture of the invention, foam stabilizers, catalysts or catalystcombination, the blowing agent, water for example, and any furtheradditives, such as flame retardency, color, biocides, etc., depending onthe formula for the flexible polyurethane foam. An activator solution ofthis type may also be a composition according to the invention.

With regard to the blowing agents, a distinction is made betweenchemical and physical blowing agents. The chemical blowing agentsinclude, for example, water, the reaction of which with the isocyanategroups leads to formation of CO₂. The apparent density of the foam canbe controlled by the amount of water added, with the preferred amountsof water used lying, for example, between 0.5 and 10 parts, preferablybetween 1 and 7 parts, more preferably between 1 and 5 parts, based on100.0 parts of polyol. In addition, it is alternatively and/or elseadditionally possible to use physical blowing agents. These are liquidswhich are inert to the formulation constituents and have boiling pointsbelow 100° C., preferably below 50° C., especially between −50° C. and30° C., at atmospheric pressure, such that they evaporate under theinfluence of the exothermic polyaddition reaction. Examples of suchliquids usable with preference are ketones such as acetone and/or methylethyl ketone, hydrocarbons such as n-, iso- or cyclopentane, n- orisobutane and propane, cyclohexane, ethers such as dimethyl ether anddiethyl ether, halogenated hydrocarbons such as methylene chloride,tetrafluoroethane, pentafluoropropane, heptafluoropropane,pentafluorobutane, hexafluorobutane and/or dichloromonofluoroethane,trichlorofluoromethane, dichlorotetrafluoroethane and1,1,2-trichloro-1,2,2-trifluoroethane. In addition, it is also possibleto use carbon dioxide. It is also possible to use mixtures of theselow-boiling liquids with one another and/or with other substituted orunsubstituted hydrocarbons. The foaming may proceed either understandard pressure or under reduced pressure (VPF technology).

The amount of the physical blowing agent in this case is preferably inthe range between 1 and 120 parts by weight, more particularly between 1and 15 parts by weight, and the amount of water is preferably in therange between 0.5 to 10 parts by weight, more particularly 1 to 5 partsby weight, based in each case on 100 parts by weight of polyol. Carbondioxide is preferred among the physical blowing agents, and ispreferably used in combination with water as chemical blowing agent.

The inventive activator solution may additionally comprise all thecustomary additives known for activator solutions in the prior art. Theadditions may be selected from the group encompassing flame retardants,UV stabilizers, dyes, biocides, pigments, cell openers, crosslinkers andthe like.

For the production of a PU foam of the invention, more particularly aflexible polyurethane foam, a preferred procedure involves reacting amixture (mix) of polyol, di- or polyfunctional isocyanate, inventiveadditive, i.e. compounds of the formula (I) or antioxidant mixture ofthe invention, amine catalyst, organopotassium—zinc and/or—tin compoundor other metal-containing catalysts, foam stabilizer, blowing agent,preferably water to form CO₂ and, if necessary, addition of physicalblowing agents, optionally with flame retardants, UV stabilizers, colorpastes, biocides, fillers, crosslinkers or other customary processingaids being added. Such a mixture likewise constitutes a subject of theinvention. A mixture comprising the additive for inventive use, i.e.compounds of the formula (I) or antioxidant mixture of the invention,and polyol likewise constitutes a subject of the invention.

Isocyanates used may be organic isocyanate compounds containing at leasttwo isocyanate groups. In general, useful isocyanates are the aliphatic,cycloaliphatic, araliphatic and preferably aromatic polyfunctionalisocyanates known per se. Isocyanates are more preferably used at from60 to 140 mol %, relative to the sum total of isocyanate-consumingcomponents.

Specific examples include the following: alkylene diisocyanates having 4to 12 carbon atoms in the alkylene radical, such as dodecane1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate,2-methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanateand preferably hexamethylene 1,6-diisocyanate, cycloaliphaticdiisocyanates such as cyclohexane 1,3- and 1,4-diisocyanates and anydesired mixtures of these isomers,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI),hexahydrotolylene 2,4- and 2,6-diisocyanate and the corresponding isomermixtures, dicyclohexylmethane 4,4′-, 2,2′- and 2,4′-diisocyanate and thecorresponding isomer mixtures, and preferably aromatic di- andpolyisocyanates, for example tolylene 2,4- and 2,6-diisocyanate and thecorresponding isomer mixtures, diphenylmethane 4,4′-, 2,4′- and2,2′-diisocyanate and the corresponding isomer mixtures, mixtures ofdiphenylmethane 4,4′- and 2,2′-diisocyanates, polyphenylpolymethylenepolyisocyanates, mixtures of diphenylmethane 4,4′-, 2,4′- and2,2′-diisocyanates and polyphenylpolymethylene polyisocyanates (crudeMDI) and mixtures of crude MDI and tolylene diisocyanates. Organic di-and polyisocyanates can be used individually or as mixtures thereof.

It is also possible to use isocyanates which have been modified by theincorporation of urethane, uretdione, isocyanurate, allophanate andother groups, called modified isocyanates.

Organic polyisocyanates have been found to be particularly useful andare therefore employed with preference:

tolylene diisocyanate, mixtures of diphenylmethane diisocyanate isomers,mixtures of diphenylmethane diisocyanate and polyphenylpolymethylpolyisocyanate or tolylene diisocyanate with diphenylmethanediisocyanate and/or polyphenylpolymethyl polyisocyanate or what arecalled prepolymers.

It is possible to use either TDI (tolylene 2,4- and 2,6-diisocyanateisomer mixture) or MDI (diphenylmethane 4,4′-diisocyanate). What iscalled “crude MDI” or “polymeric MDI” contains, as well as the 4,4′isomers, also the 2,4′ and 2,2′ isomers, and also higher polycyclicproducts. “Pure MDI” refers to bicyclic products composed predominantlyof 2,4′ and 4,4′ isomer mixtures or prepolymers thereof. Furthersuitable isocyanates are detailed in patent specification EP 1095968, towhich reference is made here in full.

Crosslinkers refer to low molecular weight polyfunctional compounds thatare reactive toward isocyanates. Suitable examples are polyfunctional,especially di- and trifunctional compounds having molecular weights of62 to 1000 g/mol, preferably 62 to 600 g/mol. Those used include, forexample, di- and trialkanolamines such as diethanolamine andtriethanolamine, aliphatic and aromatic diamines, for exampleethylenediamine, butylenediamine, butylene-1,4-diamine,hexamethylene-1,6-diamine, 4,4′-diaminodiphenylmethane,3,3′-dialkyl-substituted 4,4′-diaminodiphenylmethanes, tolylene-2,4- and-2,6-diamine, and preferably aliphatic diols and triols having 2 to 6carbon atoms, such as ethylene glycol, propylene glycol, 1,4-butyleneglycol, 1,6-hexamethylene glycol, 2-methylpropane-1,3-diol, glycerol andtrimethylolpropane or castor oil or pentaerythritol, and also higherpolyhydric alcohols such as sugar alcohols, for example sucrose, glucoseor sorbitol, and alkoxylated compounds of all the aforementionedexamples.

The use concentration is typically between 0.1 and 5 parts, based on100.0 parts polyol, according to the formulation, but may also differtherefrom. When MDI with a functionality f>2 is used in molded foaming,it likewise takes on a crosslinking function. Accordingly, withincreasing amount of corresponding MDI, the amount of low molecularweight crosslinkers can be reduced.

The compositions according to the invention can be used in slabstockfoaming. It is possible to use all processes known to those skilled inthe art for production of free-rise flexible polyurethane foams. Forexample, the foaming operation can be effected either in the horizontalor in the vertical direction, in batchwise or continuous systems. Theadditive compositions usable in accordance with the present inventionare similarly useful for CO₂ technology. Use in low-pressure andhigh-pressure machines is possible, in which case the formulations ofthe invention can be metered directly into the mixing chamber or elseare added upstream of the mixing chamber to one of the components whichsubsequently pass into the mixing chamber. The addition can also beeffected in the raw material tank.

Polyols suitable as polyol component for the purposes of the presentinvention are all organic substances having two or moreisocyanate-reactive groups, preferably OH groups, and also formulationsthereof. All polyether polyols and polyester polyols typically used forproduction of polyurethane systems, especially polyurethane foams, arepreferred polyols.

These may, for example, be polyether polyols or polyester polyols whichtypically bear 2 to 8 OH groups per molecule and, as well as carbon,hydrogen and oxygen, may also contain heteroatoms such as nitrogen,phosphorus or halogens; preference is given to using polyether polyols.Polyols of this kind can be prepared by known processes, for example byanionic polymerization of alkylene oxides in the presence of alkalimetal hydroxides or alkali metal alkoxides as catalysts, and withaddition of at least one starter molecule containing preferably 2 to 3reactive hydrogen atoms in bound form, or by cationic polymerization ofalkylene oxides in the presence of Lewis acids, for example antimonypentachloride or boron fluoride etherate, or by double metal cyanidecatalysis. Suitable alkylene oxides contain from 2 to 4 carbon atoms inthe alkylene moiety. Examples are tetrahydrofuran, 1,2-propylene oxide,1,2- or 2,3-butylene oxide; preference is given to using ethylene oxideand/or 1,2-propylene oxide. The alkylene oxides may be usedindividually, in alternation or as mixtures. H-functional startersubstances used are especially polyfunctional alcohols and/or amines.Alcohols used with preference are dihydric alcohols, for exampleethylene glycol, propylene glycol, or butanediols, trihydric alcohols,for example glycerol, trimethylolpropane or castor oil orpentaerythritol, and higher polyhydric alcohols, such as sugar alcohols,for example sucrose, glucose or sorbitol Amines used with preference arealiphatic amines having up to 10 carbon atoms, for exampleethylenediamine, diethylenetriamine, propylenediamine, aromatic amities,for example tolylenediamine or diaminodiphenylmethane, and also aminoalcohols such as ethanolamine or diethanolamine.

Polyester polyols can be prepared by a polycondensation reaction or byring-opening polymerization. Acid components used are, for example,succinic acid, maleic acid, maleic anhydride, adipic acid, phthalicanhydride, phthalic acid, isophthalic acid, terephthalic acid,tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalicanhydride or mixtures of said acids and/or anhydrides. Alcoholcomponents used are, for example, ethanediol, 1,2-propanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol,1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, diethylene glycol,dipropylene glycol, trimethylolpropane, glycerol, pentaerythritol ormixtures of the stated alcohols. If the alcohol component used isdihydric or polyhydric polyether polyols, the result is polyester etherpolyols which can likewise serve as starter substances for preparationof the polyether polycarbonate polyols. Preference is given to usingpolyether polyols having Mn=150 to 2000 g/mol for preparation of thepolyester ether polyols.

The polyether polyols, preferably polyoxypropylenepolyoxyethylenepolyols, typically have a functionality of 2 to 8 and number-averagedmolecular weights preferably in the range from 500 to 8000, preferably800 to 4500. Further polyols are known to those skilled in the art andcan be found, for example, in EP-A-0380993 or U.S. Pat. No. 3,346,557,to which reference is made in full.

High-elasticity flexible polyurethane foams (cold-cure foam) arepreferably produced by employing di- and/or trifunctional polyetheralcohols preferably having above 50 mol % of primary hydroxyl groups,based on the sum total of hydroxyl groups, in particular those having anethylene oxide block at the chain end or those based exclusively onethylene oxide.

Slabstock flexible foams are preferably produced by employing di- and/ortri-functional polyether alcohols having secondary hydroxyl groups,preferably above 80 mol %, in particular those having a propylene oxideblock or random propylene oxide and ethylene oxide block at the chainend, or those based exclusively on propylene oxide blocks.

A further class of polyols is of those which are obtained as prepolymersby reaction of polyol with isocyanate in a molar ratio of 100:1 to 5:1,preferably 50:1 to 10:1. Such prepolymers are preferably used in theform of a solution in polyol, and the polyol preferably corresponds tothe polyol used for preparing the prepolymers.

Yet a further class of polyols is that of the so-called filled polyols(polymer polyols). These contain dispersed solid organic fillers up to asolids content of 40% by weight or more. Those used include thefollowing:

SAN polyols: These are highly reactive polyols containing a dispersedcopolymer based on styrene-acrylonitrile (SAN).

PHD polyols: These are highly reactive polyols containing polyurea,likewise in dispersed form.

PIPA polyols: These are highly reactive polyols containing a dispersedpolyurethane, for example formed by in situ reaction of an isocyanatewith an alkanolamine in a conventional polyol.

The solids content, which is preferably between 5% and 40% by weight,based on the polyol, depending on the application, is responsible forimproved cell opening, and so the polyol can be foamed in a controlledfashion, especially with TDI, and no shrinkage of the foams occurs. Thesolids content thus acts as an essential processing aid. A furtherfunction is to control the hardness via the solids content, since highersolids contents bring about a higher hardness on the part of the foam.

The formulations with solids-containing polyols have distinctly lowerintrinsic stability and therefore tend also to additionally requirephysical stabilization in addition to the chemical stabilization due tothe crosslinking reaction.

Depending on the solids contents of the polyols, these are used alone orin a blend with the abovementioned unfilled polyols.

A further class of useful polyols is that of the so-called autocatalyticpolyols, in particular autocatalytic polyether polyols. Polyols of thiskind are based, for example, on polyether blocks, preferably on ethyleneoxide and/or propylene oxide blocks, and additionally includecatalytically active functional groups, for example nitrogen-containingfunctional groups, especially amino groups, preferably tertiary aminefunctions, urea groups and/or heterocycles containing nitrogen atoms.Through the use of such autocatalytic polyols in the production ofpolyurethane systems, especially of polyurethane foams, more preferablyof flexible polyurethane foams, the requisite amount of any catalystsused may optionally be reduced, according to application, and/or adaptedto specific desired foam properties. Suitable polyols are described, forexample, in WO0158976 (A1), WO2005063841 (A1), WO0222702 (A1),WO2006055396 (A1), WO03029320 (A1), WO0158976 (A1), U.S. Pat. No.6,924,321 (B2), U.S. Pat. No. 6,762,274 (B2), EP2104696 (B1),WO2004060956 (A1) or WO2013102053 (A1) and can be purchased, forexample, under the Voractiv™ and/or SpecFlex™ Activ trade names fromDow.

Blowing agents used may be the known blowing agents. Preferably, in theproduction of the polyurethane foam, water, methylene chloride, pentane,alkanes, halogenated alkanes, acetone and/or carbon dioxide are used asblowing agents.

The water can be added directly to the mixture or else be added to themixture as a secondary component of one of the reactants, for example ofthe polyol component, together with the latter.

In addition to physical blowing agents and any water, it is alsopossible to use other chemical blowing agents which react withisocyanates to evolve a gas, an example being formic acid.

Catalysts used in the context of this invention may, for example, be anycatalysts for the isocyanate-polyol (urethane formation) and/orisocyanate-water (amine and carbon dioxide formation) and/or isocyanatedimerization (uretdione formation), isocyanate trimerization(isocyanurate formation), isocyanate-isocyanate with CO₂ elimination(carbodiimide formation) and/or isocyanate-amine (urea formation)reactions and/or “secondary” crosslinking reactions such asisocyanate-urethane (allophanate formation) and/or isocyanate-urea(biuret formation) and/or isocyanate-carbodiimide (uretonimineformation).

Suitable catalysts for the purposes of the present invention are, forexample, substances which catalyse one of the aforementioned reactions,especially the gelling reaction (isocyanate-polyol), the blowingreaction (isocyanate-water) and/or the dimerization or trimerization ofthe isocyanate. Such catalysts are preferably nitrogen compounds,especially amines and ammonium salts, and/or metal compounds.

Suitable nitrogen compounds as catalysts, also referred to hereinafteras nitrogenous catalysts, for the purposes of the present invention areall nitrogen compounds according to the prior art which catalyse one ofthe abovementioned isocyanate reactions and/or can be used forproduction of polyurethanes, especially of polyurethane foams.

Examples of suitable nitrogen compounds as catalysts for the purposes ofthe present invention are preferably amines, especially tertiary aminesor compounds containing one or more tertiary amine groups, including theamines triethylamine, N,N-dimethylcyclohexylamine,N,N-dicyclohexylmethylamine, N,N-dimethylaminoethylamine,N,N,N′,N′-tetramethylethylene-1,2-diamine,N,N,N′,N′-tetramethylpropylene-1,3-diamine,N,N,N′,N′-tetramethyl-1,4-butanediamine,N,N,N′,N′-tetramethyl-1,6-hexanediamine,N,N,N′,N″,N″-pentamethyldiethylenetriamine,N,N,N′-trimethylaminoethylethanolamine, N,N-dimethylaminopropylamine,N,N-diethylaminopropylamine,N,N-dimethylaminopropyl-N′,N′-dipropan-2-olamine,2-[[3-(dimethylamino)propyl]methylamino]ethanol,3-(2-dimethylamino)ethoxy)propylamine,N,N-bis[3-(dimethylamino)propyl]amine,N,N,N′,N″,N″-pentamethyldipropylenetriamine,1-[bis[3-(dimethylamino)propyl]amino]-2-propanol,N,N-bis[3-(dimethylamino)propyl]-N′,N′-dimethylpropane-1,3-diamine,triethylenediamine, 1,4-diazabicyclo[2.2.2]octane-2-methanol,N,N′-dimethylpiperazine, 1,2-dimethylimidazole,N-(2-hydroxypropyl)imidazole, 1-isobutyl-2-methylimidazole,N-(3-aminopropyl)imidazole, N-methylimidazole, N-ethylmorpholine,N-methylmorpholine, 2,2,4-trimethyl-2-silamorpholine,N-ethyl-2,2-dimethyl-2-silamorpholine, N-(2-aminoethyl)morpholine,N-(2-hydroxyethyl)morpholine, 2,2′-dimorpholinodiethyl ether,N,N′-dimethylpiperazine, N-(2-hydroxyethyl)piperazine,N-(2-aminoethyl)piperazine, N,N-dimethylbenzylamine,N,N-dimethylaminoethanol, N,N-diethylaminoethanol,3-dimethylamino-1-propanol, N,N-dimethylaminoethoxyethanol,N,N-diethylaminoethoxyethanol, bis(2-dimethylaminoethyl ether),N,N,N′-trimethyl-N′-(2-hydroxyethyl)bis(2-aminoethyl) ether,N,N,N-trimethyl-N-3′-aminopropyl(bisaminoethyl) ether,tris(dimethylaminopropyl)hexahydro-1,3,5-triazine,1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene,1,5,7-triazabicyclo[4.4.0]dec-5-ene,N-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene,1,4,6-triazabicyclo[3.3.0]oct-4-ene, 1,1,3,3-tetramethylguanidine,tert-butyl-1,1,3,3-tetramethylguanidine, guanidine,3-dimethylaminopropylurea, 1,3-bis[3-(dimethylamino)propyl]urea,bis-N,N-(dimethylaminoethoxyethyl)isophoronedicarbamate,3-dimethylamino-N,N-dimethylpropionamide and2,4,6-tris(dimethylaminomethyl)phenol. Suitable nitrogenous catalystsaccording to the prior art can be purchased, for example, from Evonikunder the TEGOAMIN® trade name.

According to the application, it may be preferable that, in theinventive production of polyurethane foams, quaternized and/orprotonated nitrogenous catalysts, especially quaternized and/orprotonated tertiary amines, are used.

For possible quaternization of nitrogenous catalysts, it is possible touse any reagents known as quaternizing reagents. Preferably,quaternizing agents used are alkylating agents, for example dimethylsulphate, methyl chloride or benzyl chloride, preferably methylatingagents such as dimethyl sulphate in particular. Quaternization islikewise possible with alkylene oxides, for example ethylene oxide,propylene oxide or butylene oxide, preferably with subsequentneutralization with inorganic or organic acids.

Nitrogenous catalysts, if quaternized, may be singly or multiplyquaternized. Preferably, the nitrogenous catalysts are only singlyquaternized. In the case of single quaternization, the nitrogenouscatalysts are preferably quaternized on a tertiary nitrogen atom.

Nitrogenous catalysts can be converted to the corresponding protonatedcompounds by reaction with organic or inorganic acids. These protonatedcompounds may be preferable, for example, when, for example, a slowedpolyurethane reaction is to be achieved or when the reaction mixture isto have enhanced flow in use.

Useful organic acids include, for example, any hereinbelow recitedorganic acids, for example carboxylic acids having 1 to 36 carbon atoms(aromatic or aliphatic, linear or branched), for example formic acid,lactic acid, 2-ethylhexanoic acid, salicylic acid and neodecanoic acid,or else polymeric acids such as, for example, polyacrylic orpolymethacrylic acids. Inorganic acids used may, for example, bephosphorus-based acids, sulphur-based acids or boron-based acids.

However, the use of nitrogenous catalysts which have not beenquaternized or protonated is particularly preferred in the context ofthis invention.

Suitable metal compounds as catalysts, also referred to hereinafter asmetallic catalysts, for the purposes of the present invention are allmetal compounds according to the prior art which catalyse one of theabovementioned isocyanate reactions and/or can be used for production ofpolyurethanes, especially of polyurethane foams. They may be selected,for example, from the group of the metal-organic or organometalliccompounds, metal-organic or organometallic salts, organic metal salts,inorganic metal salts, and from the group of the charged or unchargedmetallic coordination compounds, especially the metal chelate complexes.

The expression “metal-organic or organometallic compounds” in thecontext of this invention especially encompasses the use of metalcompounds having a direct carbon-metal bond, also referred to here asmetal organyls (e.g. tin organyls) or organometallic compounds (e.g.organotin compounds). The expression “organometallic or metal-organicsalts” in the context of this invention especially encompasses the useof metal-organic or organometallic compounds having salt character, i.e.ionic compounds in which either the anion or cation is organometallic innature (e.g. organotin oxides, organotin chlorides or organotincarboxylates). The expression “organic metal salts” in the context ofthis invention especially encompasses the use of metal compounds whichdo not have any direct carbon-metal bond and are simultaneously metalsalts, in which either the anion or the cation is an organic compound(e.g. tin(II) carboxylates). The expression “inorganic metal salts” inthe context of this invention especially encompasses the use of metalcompounds or of metal salts in which neither the anion nor the cation isan organic compound, e.g. metal chlorides (e.g. tin(II) chloride), puremetal oxides (e.g. tin oxides) or mixed metal oxides, i.e. containing aplurality of metals, and/or metal silicates or aluminosilicates. Theexpression “coordination compound” in the context of this inventionespecially encompasses the use of metal compounds formed from one ormore central particles and one or more ligands, the central particlesbeing charged or uncharged metals (e.g. metal- or tin-amine complexes).The expression “metal-chelate complexes” is to be understood for thepurposes of this invention as comprehending in particular the use ofmetal-containing coordination compounds wherein the ligands have atleast two sites for coordinating or binding with the metal center (e.g.metal- or to be more precise tin-polyamine or metal- or to be moreprecise tin-polyether complexes).

Suitable metal-containing compounds, especially as defined above, ascatalysts in the sense of the present invention may be selected, forexample, from all metal-containing compounds comprising lithium, sodium,potassium, magnesium, calcium, scandium, yttrium, titanium, zirconium,vanadium, niobium, chromium, molybdenum, tungsten, manganese, cobalt,nickel, copper, zinc, mercury, aluminum, gallium, indium, germanium,tin, lead, and/or bismuth, especially sodium, potassium, magnesium,calcium, titanium, zirconium, molybdenum, tungsten, zinc, aluminum, tinand/or bismuth, more preferably tin, bismuth, zinc and/or potassium.

Suitable organometallic salts and organic metal salts, as defined above,as catalysts for the purposes of the present invention are, for example,organotin, tin, zinc, bismuth and potassium salts, in particularcorresponding metal carboxylates, alkoxides, thiolates andmercaptoacetates, for example dibutyltin diacetate, dimethyltindilaurate, dibutyltin dilaurate (DBTDL), dioctyltin dilaurate (DOTDL),dimethyltin dineodecanoate, dibutyltin dineodecanoate, dioctyltindineodecanoate, dibutyltin dioleate, dibutyltin bis(n-laurylmercaptide), dimethyltin bis(n-lauryl mercaptide), monomethyltintris(2-ethylhexyl mercaptoacetate), dimethyltin bis(2-ethylhexylmercaptoacetate), dibutyltin bis(2-ethylhexyl mercaptoacetate),dioctyltin bis(isooctyl mercaptoacetate), tin(II) acetate, tin(II)2-ethylhexanoate (tin(II) octoate), tin(II) isononanoate (tin(II)3,5,5-trimethylhexanoate), tin(II) neodecanoate, tin(II) ricinoleate,tin(II) oleate, zinc(II) acetate, zinc(II) 2-ethylhexanoate (zinc(II)octoate), zinc(II) isononanoate (zinc(II) 3,5,5-trimethylhexanoate),zinc(II) neodecanoate, zinc(II) ricinoleate, bismuth acetate, bismuth2-ethylhexanoate, bismuth octoate, bismuth isononanoate, bismuthneodecanoate, potassium formate, potassium acetate, potassium2-ethylhexanoate (potassium octoate), potassium isononanoate, potassiumneodecanoate and/or potassium ricinoleate.

In the inventive production of polyurethane foams, it may be preferableto rule out the use of organometallic salts, for example of dibutyltindilaurate.

Suitable metal-containing catalysts are generally selected withpreference such that they do not have any inherent nuisance odor, aresubstantially unobjectionable toxicologically, and endow the resultantpolyurethane systems, especially polyurethane foams, with as low a levelof catalyst-induced emissions as possible.

In the inventive production of polyurethane foams, it may be preferable,according to the application, to use incorporable/reactive or highmolecular weight catalysts. Catalysts of this kind may be selected, forexample, from the group of the metal compounds, preferably from thegroup of the tin, zinc, bismuth and/or potassium compounds, especiallyfrom the group of the metal carboxylates of the aforementioned metals,for example the tin, zinc, bismuth and/or potassium salts of isononanoicacid, neodecanoic acid, ricinoleic acid and/or oleic acid, and/or fromthe group of the nitrogen compounds, especially from the group of thelow-emission amines and/or the low-emission compounds containing one ormore tertiary amine groups, for example described by the aminesdimethylaminoethanol,N,N-dimethyl-N′,N′-di(2-hydroxypropyl)-1,3-diaminopropane,N,N-dimethylaminopropylamine,N,N,N′-trimethyl-N′-hydroxyethylbis(aminoethyl) ether,6-dimethylaminoethyl-1-hexanol, N-(2-hydroxypropyl)imidazole,N-(3-aminopropyl)imidazole, aminopropyl-2-methylimidazole,N,N,N′-trimethylaminoethanolamine,2-(2-(N,N-dimethylaminoethoxy)ethanol, N-(dimethyl-3-aminopropyl)ureaderivatives and alkylaminooxamides, such asbis(N—(N′,N′-dimethylaminopropyl))oxamide,bis(N—(N′,N′-dimethylaminoethyl))oxamide,bis(N—(N′,N′-imidazolidinylpropyl)oxamide,bis(N—(N′,N′-diethylaminoethyl))oxamide,bis(N—(N′,N′-diethylaminopropyl)oxamide,bis(N—(N′,N′-diethylaminoethyl)oxamide,bis(N—(N′,N′-diethylimino-1-methylpropyl)oxamide,bis(N-(3-morpholinopropylyl)oxamide, and the reaction products thereofwith alkylene oxides, preferably having a molar mass in the rangebetween 160 and 500 g/mol, and compounds of the general formula:

whereR18, R19=-C_(a)H_(2a+i), where a=1-4 for acyclic groupsR18, R19=—C_(b)H_(c)N_(d) where b=3-7, c=6-14, d=0-2 for cyclic groupsR20=C_(e)H_(f)O₉ where e=0-4, f=0-8, g=0-2R21=-H, —CH₃, —C₂H₅k, m=identically or differently 1-5.

Catalysts and/or mixtures of this kind are supplied commercially, forexample, under the Jeffcat® ZF-10, Lupragen® DMEA, Lupragen® API,Toyocat® RX 20 and Toyocat® RX 21, DABCO® RP 202, DABCO® RP 204, DABCO®NE 300, DABCO® NE 310, DABCO® NE 400, DABCO® NE 500, DABCO® NE 600,DABCO® NE 1060 and DABCO® NE 2039, Niax® EF 860, Niax® EF 890, Niax® EF700, Niax® EF 705, Niax® EF 708, Niax® EF 600, Niax® EF 602, Kosmos® 54,Kosmos® EF and Tegoamin® ZE 1 name.

Suitable use amounts of catalysts are guided by the type of catalyst andare preferably in the range from 0.005 to 10.0 pphp, more preferably inthe range from 0.01 to 5.00 pphp (=parts by weight based on 100 parts byweight of polyol) or 0.10 to 10.0 pphp for potassium salts.

According to the application, it may be preferable that, in theinventive production of polyurethane foams, one or more nitrogenousand/or metallic catalysts are used. When more than one catalyst is used,the catalysts may be used in any desired mixtures with one another. Itis possible here to use the catalysts individually during the foamingoperation, for example in the manner of a preliminary dosage in themixing head, and/or in the form of a premixed catalyst combination.

The expression “premixed catalyst combination”, also referred to belowas catalyst combination, encompasses, for the purposes of thisinvention, in particular, ready-made mixtures of metal-containingcatalysts and/or nitrogen-containing catalysts and/or correspondingprotonated and/or quaternized nitrogen-containing catalysts, and also,optionally, further ingredients or adjuvants such as, for example,water, organic solvents, acids to block the amines, emulsifiers,surfactants, blowing agents, antioxidants, flame retardants, foamstabilizers and/or siloxanes, preferably polyether siloxanes, which arealready present as such prior to foaming and which do not need to beadded as individual components during the foaming operation.

According to the application, it may be preferable when the sum total ofall the nitrogenous catalysts used relative to the sum total of themetallic catalysts, especially potassium, zinc and/or tin catalysts,results in a molar ratio of 1:0.05 to 0.05:1, preferably 1:0.07 to0.07:1 and more preferably 1:0.1 to 0.1:1.

In order to prevent any reaction of the components with one another,especially reaction of nitrogenous catalysts with metallic catalysts,especially potassium, zinc and/or tin catalysts, it may be preferable tostore these components separately from one another and then to feed inthe isocyanate and polyol reaction mixture simultaneously orsuccessively.

By means of the process according to the invention, a polyurethanesystem, preferably polyurethane foam, especially a flexible polyurethanefoam, is obtainable. This polyurethane system forms a further part ofthe subject-matter of the invention. The polyurethane foam in questionis notable in particular for the fact that by virtue of the use of theinventive antioxidant additive the foam is a particularly low-emissionfoam.

In one preferred embodiment of the invention the polyurethane systemcomprises 0.0001 to 10 wt %, preferably 0.001 to 5 wt %, moreparticularly 0.01 to 3 wt %, based on the total weight of thepolyurethane system, of one or more compounds of the formula (I) or ofan antioxidant mixture, as described above.

With the polyurethane system, more particularly polyurethane foam, ofthe invention, articles are obtainable which comprise or consist of thispolyurethane system, more particularly polyurethane foam. These articlesrepresent a further subject of this invention. Articles of this kindmay, for example, be furniture cushioning or mattresses.

A further subject of this invention, moreover, is a polyurethane systemcomprising the reaction products of one or more polyol components withone or more isocyanate components, where a hydroxyphenylcarboxylic esterof the formula (I)

in which

-   R is CH₂—CH(R^(I)), CH(R^(II))—CH(R^(II)), CH₂—C(R^(II))₂,    C(R^(II))₂—C(R^(II))₂,

-   -   CH₂—CH—CH₂—R^(IV), C₆H₆—CH—CH₂, or C₆H₆—C(CH₃)—CH₂, where

-   R^(I) is C₂ to C₂₄ alkyl radical or alkene radical, which may be    linear or branched

-   R^(II) is C₂ to C₂₄ alkyl radical or alkene radical, which may be    linear or branched

-   R^(III) is C₃ to C₆ alkyl radical, which is arranged linearly, and

-   R^(IV) is OH, Cl, OCH₃, OCH₂—CH₃, O—CH₂—CH═CH₂, O—CH═CH₂, molecule    residue of singly or multiply epoxidized fats or oils as mono-, di-,    and triglycerides, or molecule residue of singly or multiply    epoxidized fatty acids or their C₁-C₂₄ alkyl esters,

-   R₁ and R₂ independently of one another are straight-chain or    branched C₁-C₈ alkyl, cyclopentyl or cyclohexyl, especially    tert-butyl,

-   q is 1, 2 or 3, preferably 2 or 3, especially 2,

-   n is an integer from 1 to 30, preferably an integer from 1 to 10,    advantageously 1, 2, 3, 4, 5 or 6, e.g. 1, 2, 3 or 4, especially 1,

-   R₃ is an n-valent radical of linear or branched C₁-C₃₀ alkyl,    preferably C₁-C₁₀ alkyl, C₂-C₃₀ alkylene, interrupted in each case    optionally by one or more oxygen atoms, or (where n=1-12) is an    n-valent radical of C₅-C₁₂ cycloalkyl, or a radical    R₄—[NR₅—C_(q)H_(2q)—]_(p),

-   R₄ is hydrogen, an n-valent radical of linear or branched C₁-C₃₀    alkyl, which is optionally interrupted by one or more groups —NR₅—    or (where n=1-12) is an n-valent radical of C₅-C₁₂ cycloalkyl,

-   R₅ independently at each occurrence is hydrogen or methyl or    —C_(q)H_(2q)—, preferably hydrogen, and

-   p corresponds to the number of —[NR₅—C_(q)H_(2q)-] groups that    produces n radicals    -   —C_(q)H_(2q)— per molecule,

-   k is an integer between 0 and 50, preferably between 10 and 30,

-   m is an integer between 0 and 50, e.g. 1-40, and

-   o is an integer between 0 and 50, preferably between 0 and 30,    especially 0,

-   where (k+m+o)>10    is employed as an aging inhibitor for synthetic polymers sensitive    towards oxidative, thermal or light-induced degradation.

If in the formula (I) k, m, o>0 or k, m>0 and at the same time o=0, thesequence of the monomer units ethylene oxide, propylene oxide and(R-oxide) in the individual polymer chains 1 to n is arbitrary, and k, mand o represent average values. Moreover, the individual units (EO),(PO) and (RO) can be bonded to one another either in the form of blocks,in strict alternation or in the form of gradients.

A preferred composition of the invention for producing a polyurethanesystem, particularly polyurethane foam, may comprise polyol in amountsfrom 25 to 80 wt %, water in amounts from 1 to 5 wt %, catalysts inamounts from 0.05 to 1 wt %, physical blowing agent in amounts from 0 to25 wt % (e.g. 0.1 to 25 wt %), foam stabilizers (such as, for example,Si-containing and non-Si-containing stabilizers, especiallySi-containing and non-Si-containing organic stabilizers and surfactants)in amounts from 0.1 to 5 wt %, isocyanate in amounts from 20 to 50 wt %,and the additive for inventive use, i.e. compounds of the formula (I),or an antioxidant mixture of the invention, in amounts from 0.0001 to 10wt %, preferably 0.001 to 5 wt %, more particularly 0.01 to 3 wt %,based on the total weight of the polyurethane system. The compound ofthe formula (I) is employed in particular in the form of an antioxidantmixture of the invention, comprising compounds of the formula (I) andalso, preferably, compounds of the formula (II), more particularlycomprising compounds of the formula (I) and also compounds of theformula (II) and (III).

For preferred embodiments of these abovementioned compositions,reference is made explicitly to the preceding description.

The invention further provides the use of the polyurethane systemsobtainable in accordance with the invention as refrigerator insulation,insulant board, sandwich element, pipe insulation, sprayed foam, 1- and1.5-component can foam, imitation wood, modelling foam, packaging foam,mattresses, furniture upholstery, material in motor vehicle interiors,vehicle seat upholstery, headrest, instrument panel, interior automotivetrim, automotive roof liner, sound absorption material, steering wheel,footwear sole, carpet backing foam, filter foam, sealing foam, sealantand adhesive or for producing corresponding products, especially asmaterial in motor vehicle interiors.

A further subject of the invention is the use of compounds of theformula (I) or antioxidant mixtures, as described above, for producinglow-emission polyurethane systems, especially PU foam, with a reducedvalue for VOC and fogging. The compound of the formula (I) is employedin particular in the form of an antioxidant mixture of the invention,comprising compounds of the formula (I) and also, preferably, compoundsof the formula (II), more particularly comprising compounds of theformula (I) and also compounds of the formula (II) and (III).

A further subject of the invention is the use of compounds of theformula (I) or antioxidant mixtures, as described above, for producinglow-odor polyurethane systems, especially PU foam. The compound of theformula (I) is employed in particular in the form of an antioxidantmixture of the invention, comprising compounds of the formula (I) andalso, preferably, compounds of the formula (II), more particularlycomprising compounds of the formula (I) and also compounds of theformula (II) and (III).

A further subject of the invention is a method for lowering the totalemission of organic compounds from polyurethane systems, especiallypolyurethane foams, by adding compounds of formula (I) to thepolyurethane system, more particularly polyurethane foam, preferably inan amount of 0.0001 to 10 wt %, preferably 0.001 to 5 wt %, moreparticularly 0.01 to 3 wt %, based on the total weight of thepolyurethane system, it being possible for the addition to be madebefore, during or after the production of the polyurethane system. Thecompound of the formula (I) is employed in particular in the form of anantioxidant mixture of the invention, comprising compounds of theformula (I) and also, preferably, compounds of the formula (II), moreparticularly comprising compounds of the formula (I) and also compoundsof the formula (II) and (III).

The subject-matter of the present invention is elucidated in detailhereinafter with reference to examples, without any intention that thesubject-matter of the invention be restricted to these illustrativeembodiments.

EXAMPLES Preparation of the Inventive Additive of the Formula (I)

The hydroxyphenylcarboxylic esters were prepared by process A asdescribed above, starting from methyl3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (IVa-1).

Example 1 (Inventive)

A 250 mL three-necked flask with distillation bridge and KPG stirrer wascharged with 29.3 g of the hydroxyphenylcarboxylic ester methyl3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (IVa-1) together with61.9 g of a polyether of the general formula CH₃[CH₂CH₂O]₁₁H and 0.06 gof sodium acetate. The flask was flooded with nitrogen and the mixturewas heated to 180° C. and stirred for an hour. The flask was thenevacuated and the methanol formed was distilled off directly from thereaction mixture while stirring under reduced pressure (10 mbar) using adistillation bridge. After cooling had taken place, 6.9 g of thebenzofuran-2-one (IIa) and 1.7 g of the phosphite (IIIa) were dissolvedin the resulting liquid hydroxyphenylcarboxylic ester.

Example 2 (Inventive)

A 250 mL three-necked flask with distillation bridge and KPG stirrer wascharged with 29.3 g of the hydroxyphenylcarboxylic ester methyl3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (IVa-1) together with75.8 g of a polyether of the general formulaCH₃[CH₂CH(CH₃)O]₂[CH₂CH₂O]₁₁H and 0.55 g of titanium tetrabutoxide. Theflask was flooded with nitrogen and the mixture was heated to 180° C.and stirred for an hour. The flask was then evacuated and the methanolformed was distilled off directly from the reaction mixture whilestirring under reduced pressure (10 mbar) using a distillation bridge.After cooling had taken place, 7.9 g of the benzofuran-2-one (IIa) and2.0 g of the phosphite (IIIa) were dissolved in the resulting liquidhydroxyphenylcarboxylic ester.

Example 3 (Not Inventive)

A 250 ml three-necked flask with distillation bridge and KPG stirrer wascharged with 29.3 g of the hydroxyphenylcarboxylic ester methyl3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (IVa-1) together with15.6 g of 1-octanol and 0.2 g of para-toluenesulphonic acid. The flaskwas flooded with nitrogen and the mixture was heated to 180° C. andstirred for an hour. The flask was then evacuated and the methanolformed was distilled off directly from the reaction mixture whilestirring under reduced pressure (10 mbar) using a distillation bridge.After cooling had taken place, 3.5 g of the benzofuran-2-one (IIa) and0.9 g of the phosphite (IIIa) were dissolved in the resulting liquidhydroxyphenylcarboxylic ester.

Production of the Polyurethane Foams

For the performance tests, three typical formulations of flexiblepolyurethane foams were used, with the following compositions:

TABLE 1 Formulation I for TDI80 flexible slabstock foam applications fortesting of the anti-scorch performance (scorch = degradation of thepolyurethane) Formulation I Parts by mass (pphp) Voranol ® CP 3322¹⁾ 100Desmodur ® T 80²⁾ Index <104> 56.4 Water 4.8 TEGOAMIN ® 33³⁾ 0.2KOSMOS ® 29⁴⁾ 0.22 Fyrol ™ A300TB⁵⁾ 10.0 TEGOSTAB ® B 8242⁶⁾ 1.0Antioxidant mixture⁷⁾ 1.0 ¹⁾available from Dow Chemical; this is aglycerol-based polyether polyol having an OH number of 48 mg of KOH/g.²⁾tolylene diisocyanate T 80 (80% 2,4 isomer, 20% 2,6 isomer) from BayerMaterialScience, 3 mPa · s, 48% NCO, functionality 2. ³⁾amine catalystfrom Evonik Industries AG. ⁴⁾tin catalyst, available from EvonikIndustries AG. ⁵⁾phosphorus-based flame retardant from ICL IndustrialProducts. ⁶⁾polyether-modified polysiloxane, available from EvonikIndustries AG. ⁷⁾inventive antioxidant mixture, prepared according toExamples 1-2, non-inventive antioxidant mixture, prepared according toExample 3, or antioxidant mixture ORTEGOL ® AO 5 from Evonik IndustriesAG.

TABLE 2 Formulation II for TDI80 flexible slabstock foam applicationsfor determining the VOC and fog emissions as per DaimlerChrysler testinginstructions VDA 278 Formulation II Parts by mass (pphp) Arcol ® 1105S⁸⁾ 100 Desmodur ® T 80²⁾ Index <110> 41.6 Water 3.0 TEGOAMIN ® ZE1³⁾0.15 KOSMOS ® EF⁴⁾ 0.6 TEGOSTAB ® BF 2370⁶⁾ 0.8 Antioxidant mixture⁷⁾1.0 ²⁾tolylene diisocyanate T 80 (80% 2,4 isomer, 20% 2,6 isomer) fromBayer MaterialScience, 3 mPa · s, 48% NCO, functionality 2. ³⁾aminecatalyst from Evonik Industries AG. ⁴⁾tin catalyst, available fromEvonik Industries AG ⁶⁾polyether-modified polysiloxane, available fromEvonik Industries AG. ⁷⁾inventive antioxidant mixture, preparedaccording to Examples 1-2, non-inventive antioxidant mixture, preparedaccording to Example 3, or antioxidant mixture ORTEGOL ® AO 5 fromEvonik Industries AG. ⁸⁾available from Bayer Material Science; this is aglycerol-based polyether polyol having an OH number of 56 mg of KOH/g.

TABLE 3 Formulation III for TDI80 flexible slabstock foam applicationsfor determining the VOC and fog emissions as per DaimlerChrysler testinginstructions VDA 278 Formulation III Parts by mass (pphp) Arcol ® 1105S⁸⁾ 100 Desmodur ® T 80²⁾ Index <110> 62.9 Water 5.0 TEGOAMIN ® ZE1³⁾0.15 KOSMOS ® EF⁴⁾ 0.6 TEGOSTAB ® BF 2370⁶⁾ 1.0 Antioxidant mixture⁷⁾1.0 ²⁾tolylene diisocyanate T 80 (80% 2,4-isomer, 20% 2,6-isomer) fromBayer MaterialScience, 3 mPa · s, 48% NCO, functionality 2. ³⁾aminecatalyst from Evonik Industries AG. ⁴⁾tin catalyst, available fromEvonik Industries AG ⁶⁾polyether-modified polysiloxane, available fromEvonik Industries AG. ⁷⁾inventive antioxidant mixture, preparedaccording to Examples 1-2, non-inventive antioxidant mixture, preparedaccording to Example 3, or antioxidant mixture ORTEGOL ® AO 5 fromEvonik Industries AG. ⁸⁾available from Bayer Material Science; this is aglycerol-based polyether polyol having an OH number of 56 mg of KOH/g.

General Procedure for Production of the Foams

The foams were produced at 22° C. and air pressure 753 mmHg according tothe details which follow. For the production of the polyurethane foamsfor the microwave test, 100 g of polyol were used in each case; for theproduction of the polyurethane foam for the oven test and the odortesting, 300 g of polyol were used in each case; for the production ofthe polyurethane foams for determining the VOC and fog emissions, 500 gof polyol were used in each case; the other formulation constituentswere converted accordingly.

For example, 1.0 part (1.0 pphp) of a component here denoted 1 g of thissubstance per 100 g of polyol.

For the foaming, the polyol, water, catalyst (amine(s) and/or the tincompound), stabilizer and the antioxidant mixture used were mixedthoroughly with stirring. Following the addition of the isocyanate,stirring took place with a stirrer at 3000·rpm for 7 seconds and themixture was poured into a paper-lined wooden box. Resultant flexiblepolyurethane foams were subjected to the performance tests describedbelow.

For the demonstration of the anti-scorch performance of the presentinvention, a formulation was selected which is water-blown and freelyrisen (foam is able to rise unhindered; not molded foams). The amount ofwater was chosen as 4.8 parts per 100 parts polyol mixture. On the basisof this amount of water, a density of about 21 kg/m³ can be expected. Interms of density and amount of water, therefore, the formulation istypical of flexible polyurethane foam grades which are currently in usein the industry.

For the determination of the VOC and fog emissions, two differentformulations were selected, but both were water-blown and freely risen(foam is able to rise unhindered; not molded foams). In the first case,the amount of water was chosen as 3 parts per 100 parts polyol; in thesecond case, 5 parts of water were used per 100 parts polyol. In thisway, foams having densities of approximately 30 kg/m³ and 17 kg/m³ wereobtained, respectively. As a result of the different amounts of water inthe formulations, different temperatures ought to be generated duringthe foaming operation, and accordingly the influence of the temperaturein the foam on emissions investigated.

Performance Tests

The foams produced were rated on the basis of the following physicalproperties:

-   -   a) Foam settling after the end of the rise phase (=fall-back):        -   The fall-back, or the further rise, is found from the            difference in the foam height after direct blow-off and            after 3 minutes after foam blow-off. The foam height is            measured at the maximum in the middle of the foam crest by            means of a needle secured to a centimeter scale. A negative            value here describes the settling of the foam after            blow-off; a positive value correspondingly describes the            further rise of the foam.    -   b) Foam height is the height of the freely risen foam formed        after 3 minutes. Foam height is reported in centimeters (cm).    -   c) Rise time        -   The period of time between the end of mixing of the reaction            components and the blow-off of the polyurethane foam.    -   d) Density        -   The determination is made, as described in DIN EN ISO            845:2009-10, by measurement of the apparent density. The            density is reported in kg/m³.    -   e) Porosity        -   The permeability of the foam was determined in accordance            with DIN EN ISO 4638:1993-07 by a dynamic pressure            measurement on the foam. The dynamic pressure measured was            reported in mm water column, with the lower dynamic pressure            values then characterizing the more open foam. The values            were measured in the range from 0 to 300 mm. The dynamic            pressure was measured by means of an apparatus comprising a            nitrogen source, a reducing valve with manometer, a            screw-thread flow regulator, a wash bottle, a flow meter, a            T-piece, a nozzle head and a scaled glass tube filled with            water. The applicator nozzle has an edge length of 100×100            mm, a weight of 800 g, a clear width of 5 mm for the outlet            hole, a clear width of 20 mm for the lower applicator ring            and an outer diameter of 30 mm for the lower applicator            ring.        -   The measurement is effected by adjusting the nitrogen supply            pressure to 1 bar with the reducing valve and adjusting the            flow rate to 480 l/h. The amount of water in the scaled            glass tube is adjusted such that no pressure differential is            built up and none can be read off. For the analysis of the            test specimen having dimensions of 250×250×50 mm, the nozzle            head is placed onto the corners of the test specimen, flush            with the edges, and once onto the (estimated) middle of the            test specimen (in each case on the side with the greatest            surface area). The result is read off when a constant            dynamic pressure has been established.        -   Evaluation is effected by forming the average of the five            measurements obtained.

Measurement of Foam Emissions (VOC and Fog Value) Based on Test MethodVDA 278 in the Version Dated October 2011:

The method is used to ascertain emissions from non-metallic materialswhich are employed for moldings within motor vehicles. The emission ofvolatile organic compounds (VOC value, 30 minutes at 90° C.) and alsothe fraction of condensable substances (fog value, 60 minutes at 120°C.) was determined in accordance with testing protocol VDA 278 in theversion of October 2011. Described below is the procedure for thecorresponding thermodesorption with subsequent gas chromatography/massspectrometry coupling (GC/MS).

-   a) Measurement technique: The thermal desorption was conducted with    a “TDS2” thermal desorber with autosampler from Gerstel, Mülheim, in    conjunction with an Agilent 7890/5975 GC/MSD system.-   b) Measurement conditions for VOC measurements are reported in    tables 4 and 5.

TABLE 4 Thermal desorption analysis parameters for the VOC analysis runThermal desorption Gerstel TDS2 Desorption temperature 90° C. Desorptiontime 30 min Flow rate 65 ml/min Transfer line 280° C. Cryofocusing KAS 4Liner glass evaporator tube with silanized glass wool Temperature −150°C.

TABLE 5 Gas chromatography-mass spectrometry analysis parameters for theVOC analysis run GC capillary - GC Agilent 7890 Injector PTV split 1:50Temperature programme −150° C.; 1 min; 

 10° C./s; 280° C. Column Agilent 19091B-115, Ultra 2, 50 m * 0.32 mm FT0.5 μm Flow rate 1.3 ml/min const. flow Temperature programme 50° C.; 2min; 

 3° C./min; 92° C.;

 5° C./min; 160° C.; 

 10° C./min; 280° C., 20 min Detector Agilent MSD 5975 Mode Scan 29-350amu 2.3 scans/sec Evaluation Evaluation of the total ion currentchromatogram by calculation as toluene equivalent

-   c) Calibration: For calibration, 2 μl of a mixture of toluene and    hexadecane in methanol (each at 0.125 mg/ml) were introduced into a    cleaned adsorption tube packed with Tenax® TA (mesh 35/60) and    measured (desorption 5 min; 280° C.).-   d) Tenax TA is a porous polymer resin based on 2,6-diphenylene    oxide, obtainable, for example, from Scientific Instrument Services,    1027 Old York Rd., Ringoes, N.J. 08551.-   e) Sample preparation for VOC measurement: 15 mg of foam were    positioned in three sample portions in a thermal desorption tube.    Care was taken not to compress the foam.-   f) Sample preparation for fog measurement: The same foam sample was    used as for the VOC analysis. With regard to the measurement    arrangement, the VOC analysis was always conducted first and the fog    analysis thereafter, ensuring a constant separation between each of    the corresponding VOC and fog analyses by means of an autosampler    system.-   g) The fog measurement conditions are shown in tables 6 and 7.

TABLE 6 Thermal desorption analysis parameters for the fog analysis runThermal desorption Gerstel TDS2 Desorption temperature 120° C.Desorption time 60 min Flow rate 65 ml/min Transfer line 280° C.Cryofocusing KAS 4 Liner glass evaporator tube with silanized glass woolTemperature −150° C.

TABLE 7 Gas chromatography-mass spectrometry analysis parameters for thefog analysis run GC capillary - GC Agilent 7890 Injector PTV split 1:50Temperature programme −150° C.; 1 min; 

 10° C./s; 280° C. Column Agilent 19091B-115, Ultra 2, 50 m * 0.32 mm FT0.5 μm Flow rate 1.3 ml/min const. flow Temperature programme 50° C.; 2min; 

 25° C./min; 160° C.;

 10° C./min; 280° C.; 20 min Detector Agilent MSD 5975 Mode Scan 29-450amu 2.3 scans/sec Evaluation Evaluation of the total ion currentchromatogram by calculation as hexadecane equivalent

-   h) Calibration: For calibration, 2 μl of a mixture of toluene and    hexadecane in methanol (each at 0.125 mg/ml) were introduced into a    cleaned adsorption tube packed with Tenax® TA (mesh 35/60) and    measured (desorption 5 min; 280° C.).

For the measurement of the emissions, the foams used were those preparedaccording to formulations II and III and using 500 g of polyol.

Testing of the Anti-Scorch Performance

-   -   a) Microwave test        -   The foams obtained by using 100 g of polyol by conversion            according to formulation I were irradiated, after the liquid            mixture had been poured into the paper-lined wooden boxes,            for three minutes in a microwave oven at 1000 W for 80            seconds. The foams were then slit open vertically in the            center and the core discoloration was appraised visually.            Slight core discoloration was rated +, moderate core            discoloration ++, and severe core discoloration +++. A            rating of − was given for no perceptible discoloration.    -   b) Oven test        -   The foams obtained using 300 g of polyol by conversion            according to formulation I were placed in a drying cabinet            at 150° C. for 5 minutes, 3 minutes after the end of the            rise time. The paper was then removed and the foam was            heated at 180° C. for a further 2 hours. First of all a 3 cm            layer is cut off from the bottom. The core discoloration is            assessed visually in the subsequent 5 cm layer. Slight core            discoloration was rated +, moderate core discoloration ++,            and severe core discoloration +++. A rating of − was given            for no perceptible discoloration.

Odor Testing of the Resulting Foams

The completed foams, prepared from 300 g of polyol according toformulation I, were packed in odor-neutral plastic bags and stored in anairtight manner. For the odor assessment of the foam, cubes measuring 10cm×10 cm×10 cm were cut out and transferred to jars with a volume of 1l, from which the samples were smelled. The jars were closed with ascrew lid. The odor test took place after storing the jars for 24 hoursat 22° C.

The odor test was assessed by a panel of 10 trained odor testers. Theywere questioned here about the intensity of the odor; a low odor levelwas rated +, moderate odor ++, and high odor +++.

Results of the Foaming Operations

The inventive additives of Examples 1 and 2, the non-inventive additivedescribed in Example 3, and the commercially available antioxidantmixture ORTEGOL® AO 5 from Evonik Industries AG were tested for theirproperty of inhibiting core discoloration during the foaming operation,in formulation I, and the resulting foams as described above were eithermicrowave-irradiated or heated in an oven. The foams were then cut openand the core discoloration was assessed visually.

In relation to the emissions, the inventive additives of Examples 1 and2, the non-inventive additive described in Example 3, and thecommercially available antioxidant mixture ORTEGOL® AO 5 from EvonikIndustries AG were foamed in formulations II and III, and the VOC andfog emissions were determined as described above according to VDA 278(October 2011).

The results are reproduced in Tables 8-11 below.

As shown in Table 8, without the use of an antioxidant, formulation Igives rise to flexible polyurethane foams which exhibit severe corediscoloration (Table 8, entry 1) in both scorching tests (microwave andoven tests). When using 1 pphp of the comparative antioxidant mixtureORTEGOL® AO 5 from Evonik Industries AG, the core discoloration observedwas moderate in the microwave test and slight in the oven test (Table 8,entry 2). The non-inventive antioxidant mixture, prepared according toExample 3, likewise yielded flexible polyurethane foams having moderatecore discoloration in the microwave test and slight core discolorationin the oven test (Table 8, entry 5). By using 1 pphp of the inventiveantioxidant mixtures (Examples 1 and 2), improved discoloration valueswere observable both in the microwave test and in the oven test (Table8, entries 3 and 4). Foams characterized by the use of 1 pphp of theantioxidant mixtures ORTEGOL® AO 5 or the non-inventive antioxidantmixture, prepared according to Example 3, have extremely high emissionvalues, whereas foams prepared by using 1 pphp of the inventiveantioxidant mixtures according to Example 1 and 2 exhibited very low VOCand fog emission values. These foams were produced according toformulation II (3 pphp H₂O) or according to formulation III (5 pphp H₂O)and the emissions were determined in accordance with VDA 278. Nosignificant differences were apparent for the individual antioxidantmixtures in the two different formulations, and so the effect ofdifferent temperatures during the foaming operation on the emissionscharacteristics can be considered to be negligible. It was neverthelesspossible to show that the additive mixtures of the invention, both inthe VOC area and in the fog area, exhibited far lower emissions (Table9, entries 7 and 8; Table 10, entries 11 and 12) than the commerciallyavailable antioxidant mixture ORTEGOL® AO 5 and the non-inventiveantioxidant mixture prepared in Example 3 (Table 9, entries 6 and 9;Table 10, entries 10 and 13).

As Table 11 shows, the intensity of the odor of the foams produced usingthe inventive additives from Examples 1 and 2 (entries 15-16) wasconsistently assessed as being lower than the odor of the foam producedwith the comparative antioxidant mixture ORTEGOL® AO 5 from EvonikIndustries AG (entry 14). Similarly, the foam produced with theantioxidant mixture according to Example 3 (not inventive) had astronger odor than the foams produced with the two inventive antioxidantmixtures. The odor test was repeated twice more by the testers, and theaforementioned results were confirmed in precisely the same way. Fromthe results it is evident that the testers assessed a foam treated withone of the additive mixtures of the invention as having a less intenseodor.

TABLE 8 Foaming results and core discoloration when using differentantioxidants according to formulation I Rise Fall- Core Core Amount usedRise height back Porosity Density discoloration, discoloration, No.Additive [pphp] time [s] [cm] [cm] [mm] [kg/m³] microwave test oven test1 Reference 0 96 21.5 0.2 9 20.7 +++ +++ 2 ORTEGOL ® AO 5^(a)) 1 94 20.30.1 10 21.2 ++ + 3 Ex. 1^(b)) 1 98 21.0 0.2 8 21.1 + − 4 Ex. 2^(b)) 1 9821.3 0.2 8 21.0 + − 5 Ex. 3^(c)) 1 96 21.0 0.2 7 21.1 ++ +^(a))Comparative antioxidant mixture from Evonik Industries AG^(b))inventive additives prepared according to Examples 1 and 2^(c))Non-inventive additive, prepared according to Example 3 − nodiscoloration apparent + slight discoloration ++ moderate discoloration+++ severe discoloration

TABLE 9 Foaming results and VOC and fog emissions when using differentantioxidants according to formulation II Fall- Amount used Rise timeRise back Porosity Density VOC Fog No. Additive [pphp] [s] height [cm][cm] [mm] [kg/m³] [μg/m³] [μg/m³] 6 ORTEGOL ® AO 5^(a)) 1 128 32.0 0.3 929.9 61 2030 7 Ex. 1^(b)) 1 126 31.8 0.1 12 30.3 29 200 8 Ex. 2^(b)) 1126 31.7 0.2 16 30.2 30 171 9 Ex. 3^(c)) 1 124 32.0 0.2 13 30.1 41 1467^(a))Comparative antioxidant mixture from Evonik Industries AG^(b))inventive additives prepared according to Examples 1 and 2^(c))Non-inventive additive, prepared according to Example 3

TABLE 10 Foaming results and VOC and fog emissions when using differentantioxidants according to formulation III Fall- Amount used Rise timeRise back Porosity Density VOC Fog No. Additive [pphp] [s] height [cm][cm] [mm] [kg/m³] [μg/m³] [μg/m³] 10 ORTEGOL ® AO 5^(a)) 1 82 31.2 0.112 17.0 63 2022 11 Ex. 1^(b)) 1 83 30.8 0.2 13 17.3 30 181 12 Ex. 2^(b))1 81 30.9 0.1 15 17.2 30 145 13 Ex. 3^(c)) 1 80 31.0 0.1 10 17.0 43 1411^(a))Comparative antioxidant mixture from Evonik Industries AG^(b))inventive additives prepared according to Examples 1 and 2^(c))Non-inventive additive, prepared according to Example 3

TABLE 11 Odor testing of the foams according to formulation I by 10trained olfactory testers Intensity of the odor No. Additive Amount used[pphp] +++ ++ + 14 ORTEGOL ® AO 5^(a)) 1 2 6 2 15 Ex. 1^(b)) 1 0 3 7 16Ex. 2^(b)) 1 1 4 5 17 Ex. 3^(c)) 1 1 6 3 ^(a))Comparative antioxidantmixture from Evonik Industries AG ^(b))Inventive additives, preparedaccording to Examples 1 and 2 ^(c))Non-inventive additive, preparedaccording to Example 3 + slight odor ++ moderate odor +++ strong odor

What is claimed is:
 1. A compound of the formula (I)

in which R is CH₂—CH(R^(I)), CH(R^(II))—CH(R^(II)), CH₂—C(R^(II))₂,C(R^(II))₂—C(R^(II))₂,

CH₂—CH—CH₂—R^(IV), C₆H₆—CH—CH₂, or C₆H₆—C(CH₃)—CH₂, where R^(I) is C₂ toC₂₄ alkyl radical or alkene radical, which may be linear or branchedR^(II) is C₂ to C₂₄ alkyl radical or alkene radical, which may be linearor branched R^(III) is C₃ to C₆ alkyl radical, which is arrangedlinearly, and R^(IV) is OH, Cl, OCH₃, OCH₂—CH₃, O—CH₂—CH═CH₂, O—CH═CH₂,molecule residue of singly or multiply epoxidized fats or oils as mono-,di-, and triglycerides, or molecule residue of singly or multiplyepoxidized fatty acids or their C₁-C₂₄ alkyl esters, R₁ and R₂independently of one another are straight-chain or branched C₁-C₈ alkyl,cyclopentyl or cyclohexyl, especially tert-butyl, q is 1, 2 or 3, n isan integer from 1 to 30, R₃ is an n-valent radical of linear or branchedC₁-C₃₀-alkyl, interrupted in each case optionally by one or more oxygenatoms, or (especially where n=1-12) is an n-valent radical of C₅-C₁₂cycloalkyl, or a radical R₄ [NR₅—C_(q)H_(2q)—]_(p), R₄ is hydrogen, ann-valent radical of linear or branched C₁-C₃₀ alkyl, which is optionallyinterrupted by one or more groups —NR₅— or (where n=1-12) is an n-valentradical of C₅-C₁₂ cycloalkyl, R₅ independently at each occurrence ishydrogen or methyl or —C_(q)H_(2q), and p corresponds to the number of—[NR₅—C_(q)H_(2q)—] groups that produces n radicals —C_(q)H_(2q)— permolecule, k is an integer between 0 and 50, m is an integer between 0and 50, and o is an integer between 0 and 50, where (k+m+o)>10.
 2. Anantioxidant mixture comprising at least one compound of the formula (I)and a further antioxidant.
 3. An antioxidant mixture according to claim2, comprising as further antioxidant: at least one benzofuranonederivative of the formula (II)

in which n is an integer between 0 and 7, R₆ and R₇ independently of oneanother are H or C₁-C₈ alkyl,

R₈ is H or an aromatic radical where R₉ and R₁₀ independently of oneanother are H or C₁-C₆ alkyl, with not both being a C₁-C₆ alkyl, R₁₁ andR₁₂ independently of one another are H or C₁-C₆ alkyl, with not bothbeing a C₁-C₆ alkyl, R₁₃ is H or OH.
 4. The antioxidant mixtureaccording to claim 3, characterized in that the compound of the formula(I) is present in an amount of 75 to 99 wt % and the compound of theformula (II) is present in an amount of 1 to 25 wt %, wt % being basedon the total weight of the compounds of the formulae (I) and (II) used.5. The antioxidant mixture according to claim 3, further comprising aphosphite of the formula (III),

in which R₁₄, R₁₅ and R₁₆ independently of one another are an aromaticor aliphatic, linear or branched radical of C₁-C₃₀ alkyl or C₂-C₃₀alkylene, interrupted in each case optionally by one or more oxygenatoms, the phosphite being present preferably in amounts of 0.1 to 20 wt%, wt % being based on the total weight of the compounds of the formulae(I), (II) and phosphite used.
 6. A process for producing polyurethanesystems by reaction of at least one polyol component with at least oneisocyanate component in the presence of one or more catalysts whichcatalyse the isocyanate-polyol and/or isocyanate-water reactions and/orthe isocyanate trimerization, characterized in that the reaction iscarried out in the presence of one or more compounds of the formula (I)or in the presence of an antioxidant mixture according to claim 3.